Process and apparatus for coating components of a shopping cart and a product

ABSTRACT

A process and apparatus for coating components against corrosion and for durability. The process including cleaning the metal parts with cleaners and acid dips, rinsing, then dip coating the component with a nickel layer followed by a chemical sealant. The nickel-plated component may then be powder coated and cured. Alternatively, the nickel-plated component may be further layered with a dip-coated layer of chromium to produce durable and corrosion resistant properties.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a process for coating metalarticles and more particularly, a process for applying abrasion andcorrosion resistance substances to components of a shopping cart, anapparatus for applying such coatings and to shopping cart componentshaving such components.

2. Background Description

Various types of articles, such as for example, shopping carts, requireprotective coatings to withstand corrosion and abrasion while presentingan attractive appearance. Several techniques are known for coatingmetallic articles that may involve electrostatic applications ofcompounds onto the articles. Additionally, certain types of dippingprocesses are known for specific types of layering. However,individually these techniques typically do not provide high abrasionresistance and impart high strength characteristics.

In addition, protective final finishes (e.g., paint or resin typefinishes) are currently applied using a wide range of known techniquessuch as, for example, electrostatic spray. These finishes may involve awide range of materials including resins, polymers, organic paint, andthe like. However, these processes, by themselves, do not provide a highlevel of abrasion and corrosion resistance.

A layering process is needed that provides exceptionally high corrosionresistance and exceptionally strong durability against abrasion thatutilizes a low cost layering technique and is adaptable to a wide rangeof article shape, strength, and size. The process should also besuitable for use on a wide range of base metal substrates and providefor application of various final finishes.

SUMMARY OF THE INVENTION

An aspect of the present invention includes a process for plating acomponent for a shopping cart. The process includes cleaning thecomponent by immersion in a cleaning solution then rinsing the componentat least one time to remove the cleaning solution. The process furtherincludes dipping the component into a nickel bath to produce anickel-plating having a thickness of approximately 0.35-2 mil-inch. Thenickel-plated component is rinsed at least one time andelectrostatically sprayed with a powder coating, wherein thenickel-plated component produces a substantially corrosion resistantcomponent. Chromium plating may be applied directly to the nickel, in anembodiment.

Another aspect of the present invention includes a process for plating acomponent including cleaning the component by immersion in a cleaningsolution, rinsing the component at least one time and dipping thecomponent into a nickel bath to produce a nickel-plated component havinga nickel plating substantially 0.35-2 mil-inch thick. The component maybe dipped in a chromium bath to produce a nickel-chromium platedcomponent having a chromium plating substantially 0.0002-0.1 mil-inchthick.

Another aspect of the present invention provides for a means for dippingthe component into a nickel bath to produce a nickel-plated componentand a means for rinsing the nickel-plated component at least one time. Ameans is also provided for dipping the nickel-plated component in achromium bath to produce a nickel-chromium plated component having achromium plating substantially 0.0002-0.1 mil-inch. Also, a means forrinsing the nickel-chromium plated component at least one time and ameans for sealing the nickel-chromium plated component with a chemicalsealer and a means for rinsing the sealed nickel-chromium platedcomponent at least one time is provided. A means for drying thenickel-chromium plated component by heating and a means for applying apowder coating to the nickel-chromium plated component to provide afinish and a means for curing the nickel-chromium plated and powdercoated component is also provided.

In another aspect of the invention, a shopping cart having one or morecomponents is provided. The one or more components of the shopping carthave a metal like structure with a nickel chromium plating and anelectrostatic sprayed powder coating applied over the nickel chromiumplating. The nickel plating has a thickness in range of approximately0.35-2 mil-inch, the chromium plating has a thickness in a range ofapproximately 0.0002-0.1 mil-inch, and the powder coating has athickness in a range of approximately 2-6 mil-inch.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, aspects and advantages will be betterunderstood from the following detailed description of a preferredembodiment of the invention with reference to the drawings, in which:

FIGS. 1A-1C are block diagrams showing components and stages of theprocess according to the present invention; and

FIG. 2 is a block diagram showing components and stages of drying andfinishing process according to the present invention.

DETAILED DESCRIPTION OF A DETAILED EMBODIMENT OF THE INVENTION

The process of providing coatings to articles according to the presentinvention involves a multi-step process, in an embodiment, for layeringprotective metallic layers onto the article, such as components for ashopping cart or other mobile carrier, followed by an application of afinishing layer of powder coat. The layering of an article according tothis invention provides particularly durable properties againstcorrosion and abrasion and is accomplished in a low cost and practicalmanner. The present invention will be discussed with reference tocomponents of a shopping cart as an illustrative example implementingthe process of the present invention. It should be understood, however,by those of ordinary skill that the present invention is not limited tocomponents of shopping carts and may equally be used with other suitablearticles capable of undergoing the processes of the present invention.

FIGS. 1A, 1B, and 1C are block diagrams showing components and stages ofthe plating process and plating machine according to the presentinvention, as generally shown as reference numeral 5. FIGS. 1A-1C mayalso represent high level flow diagrams representative of the processsteps according to the present invention. The illustrative embodimentportrays a shopping cart frame as an article 10 for coating; however,any suitable article of manufacture may be coated using the process ofthe present invention. These articles may be made from any suitablemetal such as, for example, steel, alloys, or the like (generallymetal-like). The temperatures, layering thickness of any plating andtime period discussed throughout the process of the present inventioneach have, in an embodiment, an associated tolerance of +/−20%. Itshould also be understood that FIGS. 1A-1C, each are representative of acomponent to be dipped in an appropriate solution and then removedtherefrom.

To begin, the processes of the invention include stages of cleaning andrinsing the article in preparation of receiving coatings of nickel, andoptionally, chromium. In operation, the article 10 is loaded onto aplating machine 5 via conveyor 15, which successively moves the articlethrough various stages of the process. These stages include the dippingstages as well as, in an embodiment, spraying stages. However, asdiscussed, the dipping and spraying stages may be interchangeable, ininstances.

At stage 20, the article is immersed in a caustic soak cleaner andcomprises sodium hydroxide, having a concentration range 8 to 14 percentby volume, and surfactants and solvents at a combined concentration of 2to 8 percent by volume, operating at a temperature range of 150 to 190degrees Fahrenheit. This cleaner solution removes any foreign substancesand generally cleans the article.

This caustic soak typically lasts approximately 6-8 minutes. It is notedthat, as stated above, all temperature, concentrations, voltage,current, time and thickness ranges contemplated by the invention mayvary approximately +/−20% from the stated ranges.

At stage 25, the article is at a rinse stage for removing the causticsoak and typically lasts approximately 0.5-2 minutes for the rinse. Therinse typically is typically flowing fresh water, but may be other rinseagents, and minimizes carry-over of cleaner solution to the next processtank.

The rinse is shown as a dip, however, other methods may be used in allthe rinse steps such as, for example, a spray rinse. The article movesalong to an electro cleaner stage 30 for immersion and furtherpreparation for layering of the nickel or chromium plating. The electrocleaner may include such cleaners as, for example, a caustic cleaningsolution comprising sodium hydroxide, having a concentration range of 6to 15 percent by volume, and surfactants and chromium reducing agents ata combined concentration of 2 to 8 percent by volume, operating at atemperature range of 150 to 190 degrees Fahrenheit. The part issubjected to an anodic electrolytic cleaning process at an impressedvoltage of approximately 5 to 12 volts resulting in a current density ofapproximately 40 to 60 amperes per square foot of part surface area.

This immersion typically lasts approximately 3-4 minutes and is followedby another rinse stage 35 with a suitable rinse agent, such as water, toremove the electro cleaner. This rinse stage lasts approximately 1-2minutes. A second rinse at stage 40 may also be provided, in anembodiment, after stage 35 and may last approximately 1-2 minutes toinsure complete removal of the electro cleaner.

Still referring to FIGS. 1A-1C, the article proceeds to stage 45, whichis an electro acid immersion stage. This immersion stage lastsapproximately 3-4 minutes. The electro acid may include, for example,sulfuric acid having a concentration range of 9 to 14 percent by volume,fluoride agents having an active fluoride of 0 to 6 percent by volume,and wetting agents, operating at a temperature range of 150 to 190degrees Fahrenheit. The part is subjected to an cathodic electrolyticcleaning process at an impressed voltage of 4 to 12 volts resulting in acurrent density of approximately 5 to 30 amperes per square foot of partsurface area.

This stage further advances the cleaning of the article's surfacetypically removing any oxide scales present from the processing of themetal and is followed by another rinse stage 50 that lasts approximately0.5-2 minutes. At stage 50, another electro cleaner immersion stage 55may be provided, in an embodiment, for approximately 1-4 minutes. Theelectro cleaner may include such cleaners as, for example, a causticcleaning solution comprising sodium hydroxide, having a concentrationrange of 6 to 15 percent by volume, and surfactants and chromiumreducing agents at a combined concentration of 2 to 8 percent by volume,operating at a temperature range of 150 to 190 degrees Fahrenheit. Thepart is subjected to an anodic electrolytic cleaning process at animpressed voltage of approximately 5 to 12 volts resulting in a currentdensity of approximately 40 to 60 amperes per square foot of partsurface area.

Two rinse stages 60 and 65, similar to stage 25, are then provided toremove any electro cleaner. The stages 60 and 65 each last approximately0.5-2 minutes.

The article moves along the plating machine 5 to an acid dip stage 70wherein the article is dipped in an acid bath for approximately 1-3minutes. The acid may include an acidic cleaning solution comprisinghydrochloric acid, having a concentration of 15 to 40 percent by volume,fluoride agents having an active fluoride of 0 to 6 percent by volume,and wetting agents, operating at a temperature range of 70 to 150degrees Fahrenheit. The part is subjected to an anodic electrolyticcleaning process at an impressed voltage of 5 to 12 volts resulting in acurrent density of 40 to 60 amperes per square foot of part surfacearea. A rinse stage 75, similar too stage 25, follows for approximately0.5-2 minutes.

The conveyor 15 then transports the article 10 to a nickel plating stage80. At this stage, the article is dipped in an electrolytic nickel bathfor approximately 19-24 minutes to provide a thickness in the range of0.35-2 mil-inch. This provides a nickel-plated coating to the article.The nickel plate is then rinsed by four or more successive rinse stages85, 90, 95, and 100, each of which is approximately 0.5-2 minutes.

The article 10 may optionally enter another sequence for coating withchromium to produce a nickel-chromium layered article, or alternatively,continue directly with the rinse stage 110. In an embodiment, theadditional rinse steps may be eliminated if there is no chromiumlayering. Continuing with chromium plating, the nickel coated article 10proceeds to a chromium dipping stage 105. The nickel-coated article 10is immersed in a chromium bath for approximately 2-4 minutes thatproduces a chromium plating in the range of 0.0002 to 0.1 mil-inch. Thechromium plating includes chromium metal plating derived from tri-valentor hexavalent electrolytic process.

At stage 110, the nickel-plated, or alternatively, the nickel-chromiumplated article 10 is rinsed for approximately 0.5-2 minutes, followed bya second rinse stage 115 for about another 0.5-2 minutes, both similarto stage 25. A chemical sealer is applied at stage 120, which lasts forabout 0.5-2 minutes. The chemical sealer may include an acidic solutionand other adhesion promoters. The sealer passivates unplated surfacesand enhances subsequent metal-to-plastic adhesion. The chemical sealerstage 120 is followed by two rinse stages 125 and 130, similar to stage25. If necessary, the article 10 may be removed from the plating machine5 at this point and transferred to a drying and finishing sequence, orif the sequence is continuous, the article 10 proceeds directly to thedrying and finishing sequence.

FIG. 2 is a block diagram showing components and stages of the dryingand finishing process according to the present invention. FIG. 2 mayalso represent high level flow diagrams representative of the processsteps according to the present invention. In this sequence, the platedarticle 10 proceeds to the drying and finishing sequence, generallyshown as reference numeral 145, beginning with a drying stage 150. Inthe drying stage, the nickel coating or nickel-chromium coatings aredried in an oven. The oven temperature is nominally 325 degreesFahrenheit. The heating time is approximately 5-10 minutes (+/−20%) witha cooling time of approximately 5-10 minutes (+/−20%). Of course, thecooling time may be greater. Again, it is noted that all temperatures,drying and cooling times, etc. may vary according to the presentinvention by approximately +/−20%, or in another embodiment, more orless ranges are also contemplated for use by the invention.

The article 10 is then conveyed to the powder coating stage 160. At thisstage, a powder coating finish is applied to the article 10, typicallyby an electrostatic spraying process, although other means may beemployed by the present invention. The powder coating finish may be oneof many types including plastic, resins, polymers, or the like, and maybe of various colors. The thickness is typically 3-5 mil-inch with timein the spraying booth of approximately 1-2 minutes. The powder coatedarticle 10 then enters a curing stage 170, at which time, the article isheated in an oven to a temperature of approximately 425 degreesFahrenheit for approximately 15-20 minutes. The article 10 is thencooled for approximately 5-10 minutes producing a finished article 10 ofsubstantial corrosion resistance and high durability.

While the invention has been described in terms of embodiments, thoseskilled in the art will recognize that the invention can be practicedwith modifications and in the spirit and scope of the appended claims.

1. A process for plating a component for a shopping cart or carrying conveyance, the process comprising the steps of: cleaning the component by a cleaning solution; rinsing the component at least one time to remove the cleaning solution; dipping the component into a nickel bath to produce a nickel-plating having a thickness of approximately 0.35-2 mil-inch thick; rinsing the nickel-plated component at least one time; and electrostatically spraying a powder coating over the nickel-plating, wherein the nickel-plating and powder coat produces a substantially corrosion and abrasion resistant component.
 2. The process of claim 1, further comprising the steps of: before the electrostatic spraying step, dipping the nickel-plated component in a chromium bath to produce a chromium plating having a thickness of substantially 0.0002-0.1 mil-inch thick; and rinsing the nickel-chromium plated component at least one time after the dipping the nickel-plated component in the chromium bath step.
 3. The process of claim 2, wherein each of the rinsing steps is approximately 0.5-2 minutes.
 4. The process of claim 2, further comprising the step of: sealing the nickel-chromium plated component with a chemical sealer before the electrostatic spraying step; and rinsing the chemical sealer from the nickel-chromium plated component.
 5. The process of claim 2, further comprising the steps of: drying the nickel-chromium plated component; applying the powder coating after the drying step to the nickel-chromium plated component; and after the drying step, curing the nickel-chromium plated component.
 6. The process of claim 5, wherein the drying step includes heating the nickel-chromium plated component approximately 5-10 minutes, +/−20%, in a temperature of about 325 degrees F., +/−20%, and then cooling the nickel-chromium plated component.
 7. The process of claim 2, wherein the applying a powder coating step takes approximately 1-2 minutes.
 8. The process of claim 5, wherein in the curing step includes heating the nickel-chromium component to about 425 degrees F. for about 15-20 minutes.
 9. The process of claim 8, further includes cooling the nickel-chromium component.
 10. The process of claim 2, wherein the applying the powder coating includes electrostatically spraying the powder coating to produce a thickness of about 3-5 mil-inch.
 11. The process of claim 1, wherein cleaning the component step includes immersing the component in a caustic cleaner.
 12. The process of claim 1, wherein the cleaning the component step includes immersing the component in a first electro cleaner.
 13. The process of claim 12, wherein the cleaning step includes immersing the component in a second electro cleaner.
 14. The process of claim 13, further comprising the step of immersing the component in an acid dip after the second electro cleaner step.
 15. The process of claim 1, further comprising the step of: before the electrostatically sealing step, sealing the nickel plated component with a chemical sealer; and rinsing the sealed nickel plated component at least one time.
 16. The process of claim 1, further comprising the steps of: before the electrostatically spraying step, drying the nickel plated component by heating to a temperature of approximately 325 degrees F. +/−20%, and then cooling the nickel plated component; and after the electrostatically spraying step, curing the nickel plated sprayed component by heating to approximately 425 degrees F. +/−20% and then cooling.
 17. The process of claim 1, wherein the powder is applied to the nickel plated component to a thickness of about 3-5 mil-inch.
 18. A process for plating a component for a shopping cart or carrying conveyance, the process comprising the steps of: cleaning the component by immersion in a cleaning solution; rinsing the component at least one time to remove the cleaning solution; dipping the component into a nickel bath to produce a nickel-plated component having a nickel plating substantially 0.35-2 mil-inch thick; and dipping the nickel-plated component in a chromium bath to produce a nickel-chromium plated component having a chromium plating substantially 0.0002-0.1 mil-inch thick.
 19. The process of claim 18, further comprising the steps of: sealing the nickel-chromium plating with a chemical sealer; and rinsing the sealed nickel-chromium plating at least one time.
 20. The process of claim 19, further comprising the steps of: drying the nickel-chromium plated component; applying a powder coating to the nickel-chromium plated component to provide a finish; and curing the nickel-chromium plated and powder coated component.
 21. The process of claim 20, wherein the drying step includes drying the nickel-chromium plated component approximately 5-10 minutes, +/−20%, in a temperature of about 325 degrees F., +/−20%, and cooling the nickel-chromium plated component.
 22. The process of claim 20, wherein the applying a powder steps includes electrostatically spraying the powder coating to produce a powder coating thickness of about 3-5 mil-inch.
 23. The process of claim 20, wherein in the curing step includes heating the nickel-chromium plated component to approximately 425 degrees F., +/−20%, for approximately 15-20 minutes, +/−20%, and then cooling the nickel-chromium plated component.
 24. An apparatus for plating a component, comprising: a means for cleaning the component by immersion in a cleaning solution; a means for rinsing the component at least one time to remove the cleaning solution; a means for dipping the component into a nickel bath to produce a nickel-plated component having a nickel plating substantially 0.35-2 mil-inch thick; a means for rinsing the nickel-plated component at least one time, a means for dipping the nickel-plated component in a chromium bath to produce a nickel-chromium plated component having a chromium plating substantially 0.0002-0.1 mil-inch thick; a means for rinsing the nickel-chromium plated component at least one time, a means for sealing the nickel-chromium plated component with a chemical sealer; a means for rinsing the sealed nickel-chromium plated component at least one time; a means for drying the nickel-chromium plated component by heating; a means for applying a powder coating to the nickel-chromium plated component to provide a finish; and a means for curing the nickel-chromium plated and powder sprayed component.
 25. The apparatus of claim 24, wherein the means for drying the nickel-chromium plated component is an oven capable of heating to a temperature of about 325 degrees F., +/−20% for approximately 5-10 minutes, +/−20%.
 26. A shopping cart having one or more components, the one or more components of the shopping cart having a metal like structure with a nickel chromium plating and an electrostatic sprayed powder coating applied over the nickel chromium plating, the nickel having a thickness in range of approximately 0.35-2 mil-inch thick, the chromium plating having a thickness in a range of approximately 0.0002-0.1 mil-inch thick, and the powder coating having a thickness in a range of approximately 3-5 mil-inch. 